docs: def tox_configure(config):
      """Check for the presence of the added options."""
      if 'TRAVIS' not in os.environ:
          return
  
      ini = config._cfg
  
      # envlist
      if 'TOXENV' not in os.environ and not config.option.env:
          envlist = detect_envlist(ini)
          undeclared = set(envlist) - set(config.envconfigs)
          if undeclared:
              print('Matching undeclared envs is deprecated. Be sure all the '
                    'envs that Tox should run are declared in the tox config.',
                    file=sys.stderr)
              autogen_envconfigs(config, undeclared)
          config.envlist = envlist
  
      # Override ignore_outcomes
      if override_ignore_outcome(ini):
          for envconfig in config.envconfigs.values():
              envconfig.ignore_outcome = False
  
      # after
      if config.option.travis_after:
          print('The after all feature has been deprecated. Check out Travis\' '
                'build stages, which are a better solution. '
                'See https://tox-travis.readthedocs.io/en/stable/after.html '
                'for more details.', file=sys.stderr)